Titanium or alloys thereof on the surface of which an apatite layer is formed are expected as a bone repair material to be used at a portion to which a large load is applied because it has a high fracture toughness and can bond to living bone via apatite in living body. Accordingly, various methods for forming an apatite layer on the surface of a substrate made of titanium or alloys thereof have been investigated. Among these, a product obtained by immersing an alkali-treated substrate in an aqueous solution supersaturated with respect to apatite to deposit apatite is prone to produce cracking in apatite at the time of drying. Moreover, as to a product obtained by plasma-spraying apatite to a substrate, apatite is prone to crack at the time of cooling due to the difference in thermal expansion between apatite and the substrate. For this reason, there have been proposed various methods for producing a bone repair material of titanium or alloys thereof on the surface of which a titanate layer having an apatite-forming ability is formed in order to form apatite in the body and, at the same time, bond it to living bone (Patent Documents 1 to 8, Non-Patent Documents 1 to 5).    [Patent Document 1] WO 95/13100    [Patent Document 2] JP 08-299429 A    [Patent Document 3] JP 2004-183017 A    [Patent Document 4] JP 10-179717 A    [Patent Document 5] JP 10-179718 A    [Patent Document 6] JP 2000-93498 A    [Patent Document 7] JP 2006-102212 A    [Patent Document 8] JP 2000-102601 A    [Non-Patent Document 1] Kim, et al., J. Biomed. Mater. Res., Vol. 32, p. 409-417 (1996)    [Non-Patent Document 2] Nakagawa, et al., J. Mat. Sci: Mat. Med., Vol. 16, p. 985-991 (2005)    [Non-Patent Document 3] Wang, et al., Biomaterials, Vol. 23, p. 1353-1357 (2002)    [Non-Patent Document 4] Park, et al., Biomaterials, Vol. 28, p. 3306-3313 (2007)    [Non-Patent Document 5] Armitage, et al., Appl. Surf. Sci., Vol. 253, p. 4085-4093 (2007)